modemmanager: add ModemManager to packages

Signed-off-by: Nicholas Smith <nicholas.smith@telcoantennas.com.au>

net/modemmanager/README.md

@@ -0,0 +1,22 @@
+# OpenWrt ModemManager
+
+## Description
+
+Cellular modem control and connectivity
+
+Optional libraries libmbim and libqmi are available.  Optional mbim-utils and qmi-utils are available.
+Your modem may require additional kernel modules.
+
+## Usage
+
+# Once installed, you can configure the 2G/3G/4G modem connections directly in
+   /etc/config/network as in the following example:
+
+    config interface 'broadband'
+        option device   '/sys/devices/platform/soc/20980000.usb/usb1/1-1/1-1.2/1-1.2.1'
+        option proto    'modemmanager'
+        option apn      'ac.vodafone.es'
+        option username 'vodafone'
+        option password 'vodafone'
+        option pincode  '7423'
+        option lowpower '1'